condition mean min max ZT0-3 5.158135 4.050965 5.738775 ZT4-7 5.44076 5.44076 5.44076 ZT8-11 4.73102 4.73102 4.73102 ZT12-15 8.08024 7.6945 8.46598 ZT16-19 7.327725 7.327725 7.327725 ZT20-23 7.42519 7.42519 7.42519